CN201134233Y - Phase-locked active current control circuit - Google Patents

Abstract

A phase-locked real power current control circuit is composed of a direct current source, an electronic switch, a driving transformer, a phase detection unit, a current interception unit and a square wave controller; the direct current power supply switches a direct current signal into a square wave signal through the electronic switch to drive the transformer to push the load, the electronic switch outputs the square wave signal to the phase detection unit at the same time, the phase detection unit detects the phase signal of the square wave and outputs the detection signal to the current interception unit, the detection signal is compared with the current intercepted by the electronic switch, the driving transformer or the load by the current interception unit, and the comparison result is fed back to the square wave controller, so that the actuation frequency of the electronic switch is controlled. The utility model discloses a phase place is listened unit and electric current and is intercepted the unit to the square wave has the principle of same phase place with the primary harmonic, so follow the wave form of square wave and come the intercepting electric current, and then control side wave controller comes the stable electronic switch that switches, reaches control and maintains the stable purpose of load.

Description

Phase-locked active current control circuit

technical field

The utility model relates to a phase-locked active current control circuit, in particular to a control circuit capable of maintaining and balancing the brightness of a lamp tube of an LCD backlight source.

Background technique

Please refer to FIG. 1A, FIG. 1B and FIG. 1C, which are diagrams of the existing load current feedback control architecture. It can be seen from the figure that the DC power supply 11 switches the DC signal into a square wave signal through the electronic switch 12 for driving the transformer 13 to drive the load. 4, and the current detection unit 14 detects the current signal of the electronic switch 12 (as shown in Figure 1A), the drive transformer 13 (as shown in Figure 1B) or the load 4 (as shown in Figure 1C), and the signal Feed back to the square wave controller 15 to further control the actuation frequency of the electronic switch 12 .

Although the above control architecture can achieve the purpose of feedback control, there are the following problems:

1. Since the current flowing through the load is composed of I _R , I _L , and I _C , if the load changes, I _R , _IL , and I _C will change synchronously, which will affect the feedback control and cause problems such as difficult control.

2. When the above-mentioned control structure is applied to the control of LCD backlight, it often causes the problem of uneven brightness of the light source.

Contents of the invention

The purpose of this utility model is to provide a phase-locked active current control circuit. Through the phase detection unit and the current interception unit, the square wave and the first harmonic have the same phase, so the current can be intercepted according to the square wave waveform. , and then the square wave controller can be controlled to switch the electronic switch stably, so as to achieve the purpose of controlling and maintaining the load stability.

Another object of the present invention is to provide a phase-locked real power current control circuit, which can effectively balance the current of the lamp tube when used in the control of the LCD backlight source, so as to achieve the purpose of maintaining the uniform brightness of the lamp tube.

Another purpose of the utility model is to provide a phase-locked active current control circuit, which has the advantages of improving the stability of the product, prolonging the service life and reducing the cost of the product.

In order to achieve the above purpose, the utility model provides a phase-locked active current control circuit, which is composed of a DC current source, an electronic switch, a drive transformer, a phase detection unit, a current interception unit and a square wave controller; the DC power supply The DC signal is switched into a square wave signal through the electronic switch for driving the transformer to drive the load, and the electronic switch will output the square wave signal to the phase detection unit at the same time, and the phase signal of the square wave is detected by the phase detection unit, and Output the detection signal to the current interception unit, the detection signal will be compared with the current intercepted by the current interception unit in the electronic switch, drive transformer or load, and the comparison result will be fed back to the square wave controller to control the electronic The operating frequency of the switch.

Another solution of the present invention is to provide a phase-locked real power current control circuit, including: a DC power supply, providing a DC signal to the electronic switch; an electronic switch, receiving the DC signal output by the DC power supply, and switching it into a square The wave signal is output to the driving transformer and the phase detection unit; a driving transformer receives the square wave signal output by the electronic switch, and outputs it to the load after boosting processing; a phase detection unit receives the square wave signal output by the electronic switch , and can detect the phase signal of the square wave, and output the detection signal to the current interception unit; a current interception unit receives the detection signal output by the phase detection unit, and is in phase with the current intercepted by the drive transformer comparing and feeding back the comparison result to the square wave controller; the square wave controller receives the comparison result output by the current intercept unit and controls the operating frequency of the electronic switch according to the result.

Another solution of the present invention is to provide a phase-locked real power current control circuit, including: a DC power supply, which provides a DC signal to the electronic switch; an electronic switch, which receives the DC signal output by the DC power supply and switches it into a square The wave signal is output to the driving transformer and the phase detection unit; a driving transformer receives the square wave signal output by the electronic switch, and outputs it to the load after boosting processing; a phase detection unit receives the square wave signal output by the electronic switch , and can detect the phase signal of the square wave, and output the detection signal to the current interception unit; a current interception unit receives the detection signal output by the phase detection unit, and compares it with the current intercepted by the load , and feed back the comparison result to the square wave controller; the square wave controller receives the comparison result output by the current intercept unit, and controls the actuation frequency of the electronic switch according to the result.

Compared with the prior art, the utility model has the following advantages and positive effects due to the adoption of the above-mentioned technical scheme:

1. The phase-locked active current control circuit of the present utility model adopts the principle that the square wave and the first harmonic have the same phase through the phase detection unit and the current interception unit, so the current can be intercepted according to the waveform of the square wave, and then can be Control the square wave controller to switch the electronic switch stably to achieve the purpose of controlling and maintaining the load stability.

2. When the phase-locked active current control circuit of the present invention is applied to the control of LCD backlight, it can effectively balance the current of the lamp tubes and achieve the purpose of maintaining uniform lighting of the lamp tubes.

3. The phase-locked active current control circuit of the utility model has the advantages of improving the stability of the product, prolonging the service life and reducing the cost of the product.

Description of drawings

Fig. 1A, Fig. 1B, Fig. 1C are structure diagrams of existing load current feedback control;

FIG. 2A is an equivalent circuit diagram (1) of the load current feedback control architecture;

2B is an equivalent circuit diagram (2) of the load current feedback control architecture;

3A is a schematic diagram of voltage and current analysis of the load current feedback control framework;

3B is a schematic diagram of voltage and average current analysis of the load current feedback control framework;

FIG. 3C is a schematic diagram of square wave voltage and first harmonic analysis of the load current feedback control framework;

Fig. 4A is a schematic diagram of the first implementation structure of the phase-locked active current control circuit of the present invention;

FIG. 4B is a schematic diagram of the second implementation structure of the phase-locked active current control circuit; and

FIG. 4C is a schematic diagram of the structure of the third embodiment of the phase-locked active current control circuit.

Detailed ways

The phase-locked active current control circuit of the present invention will be further described in detail in conjunction with the accompanying drawings.

Please refer to FIG. 2A, which is an equivalent circuit diagram (1) of the load current feedback control framework. It can be seen from the figure that the electronic switch 21 can generate a square wave signal 22, and the driving transformer 23 and the load 24 can be regarded as resistors. (R), inductance (L), capacitance (C) combination.

Please refer to FIG. 2B, which is the equivalent circuit diagram (2) of the load current feedback control framework. It can be seen from the figure that the square wave signal 22 is analyzed by Fourier, and the first harmonic signal with the largest energy is taken, which is a sine wave signal 25 .

Please refer to FIG. 3A, which is a schematic diagram of the voltage and current analysis of the load current feedback control framework. It can be seen from the figure that in the above-mentioned FIG. 2A, the driving transformer and the load can be regarded as resistance (R), inductance (L), capacitance ( C) The combination of parallel connection, and the voltage (V) is applied at both ends, and the currents flowing through the resistance (R), inductance (L), and capacitance (C) are I _R , _IL , and I _C respectively, and the voltage ( V) and I _R , I _L , I _C current analysis, it can be found that the phase of the voltage (V) and I _R current is the same.

Please refer to Figure 3B, which is a schematic diagram of the voltage and average current analysis of the load current feedback control framework. It can be seen from the figure that both I _{L (average)} and I _{C (average)} are 0, and only I _{R (average)} is the active current .

Please refer to Figure 3C, which is a schematic diagram of square wave voltage and first harmonic analysis of the load current feedback control framework. It can be seen from the figure that after comparing the square wave signal with the first harmonic signal, it can be found that the square wave signal and the first harmonic signal The same phase, so the current can be intercepted according to the waveform of the square wave signal.

Please refer to Fig. 4A, which is a schematic diagram of the first implementation structure of the phase-locked active current control circuit of the present invention. It can be seen from the figure that the phase-locked active current control circuit 3 of the present invention includes:

A DC power supply 31 provides a DC signal to the electronic switch 32;

An electronic switch 32 receives the DC signal output by the DC power supply 31, and switches it into a square wave signal and outputs it to the drive transformer 33 and the phase detection unit 34;

A drive transformer 33, which receives the square wave signal output by the electronic switch 32, and outputs it to the load 4 for use after step-up processing;

A phase detection unit 34 receives the square wave signal output by the electronic switch 32, and can detect the phase signal of the square wave, and outputs the detection signal to the current interception unit 35;

A current interception unit 35 receives the detection signal output by the phase detection unit 34, compares it with the current intercepted by the electronic switch 32, and feeds back the comparison result to the square wave controller 36;

The square wave controller 36 receives the comparison result output by the current intercept unit 35 and controls the operating frequency of the electronic switch 32 according to the result.

Please refer to Fig. 4B, which is a schematic diagram of the second implementation structure of the phase-locked active current control circuit of the present invention. It can be seen from the figure that the phase-locked active current control circuit 3 of the present invention includes:

A DC power supply 31 provides a DC signal to the electronic switch 32;

An electronic switch 32 receives the DC signal output by the DC power supply 31, and switches it into a square wave signal and outputs it to the drive transformer 33 and the phase detection unit 34;

A drive transformer 33, which receives the square wave signal output by the electronic switch 32, and outputs it to the load 4 for use after step-up processing;

A phase detection unit 34 receives the square wave signal output by the electronic switch 32, and can detect the phase signal of the square wave, and outputs the detection signal to the current interception unit 35;

A current interception unit 35 receives the detection signal output by the phase detection unit 34, compares it with the current intercepted by the drive transformer 33, and feeds back the comparison result to the square wave controller 36;

The square wave controller 36 receives the comparison result output by the current intercept unit 35 and controls the operating frequency of the electronic switch 32 according to the result.

Please refer to Figure 4C, which is a schematic diagram of the third implementation structure of the phase-locked active current control circuit of the present invention. It can be seen from the figure that the phase-locked active current control circuit 3 of the present invention includes:

A DC power supply 31 provides a DC signal to the electronic switch 32;

An electronic switch 32 receives the DC signal output by the DC power supply 31, and switches it into a square wave signal and outputs it to the drive transformer 33 and the phase detection unit 34;

A drive transformer 33, which receives the square wave signal output by the electronic switch 32, and outputs it to the load 4 for use after step-up processing;

A phase detection unit 34 receives the square wave signal output by the electronic switch 32, and can detect the phase signal of the square wave, and outputs the detection signal to the current interception unit 35;

A current interception unit 35 receives the detection signal output by the phase detection unit 34, compares it with the current intercepted by the load 4, and feeds back the comparison result to the square wave controller 36;

The square wave controller 36 receives the comparison result output by the current intercept unit 35 and controls the operating frequency of the electronic switch 32 according to the result.

Compared with other prior art, the phase-locked active current control circuit provided by the utility model has the following advantages:

1. The phase-locked active current control circuit of the present utility model uses the phase detection unit and the current interception unit to use the principle that the square wave and the first harmonic have the same phase, so the current can be intercepted according to the waveform of the square wave, and then The square wave controller can be controlled to switch the electronic switch stably to achieve the purpose of controlling and maintaining the load stability.

2. When the phase-locked active current control circuit of the present invention is applied to the control of LCD backlight, it can effectively balance the current of the lamp tubes and achieve the purpose of maintaining uniform lighting of the lamp tubes.

3. The phase-locked active current control circuit of the present invention has the advantages of improving the stability of the product, prolonging the service life and reducing the cost of the product.

The above descriptions are only based on the preferred embodiments of the present utility model, and cannot limit the scope of the present utility model. Any replacement, combination, and separation of the steps of the utility model known in the technical field, as well as equivalent changes or replacements of the implementation steps of the utility model that are well known in the technical field will not exceed the disclosure and protection scope of the utility model.

Claims (3)

1. a phase-locked real merit Current Control circuit is characterized in that, comprises:

One direct current power supply provides a direct current signal to electronic switch;

One electronic switch receives the direct current signal of direct supply output, and it is switched to square-wave signal exports driving transformer and phase detection unit to;

One driving transformer receives the square-wave signal of electronic switch output, and exports to load and use after the processing of boosting;

One phase detection unit receives the square-wave signal of electronic switch output, and can detect the phase signal of square wave, and exports this detection signal to the electric current interception unit;

One electric current interception unit, the detection signal that the receiving phase detecting unit is exported, and with compare in the electric current that electronic switch intercepted, and comparative result is feedback to the square wave controller;

One square wave controller receives the comparative result of being exported by the electric current interception unit, and controls the dynamic frequency of doing of electronic switch according to this result.

2. a phase-locked real merit Current Control circuit is characterized in that, comprises:

One direct current power supply provides a direct current signal to electronic switch;

One electronic switch receives the direct current signal of direct supply output, and it is switched to square-wave signal exports driving transformer and phase detection unit to;

One driving transformer receives the square-wave signal of electronic switch output, and exports to load and use after the processing of boosting;

One phase detection unit receives the square-wave signal of electronic switch output, and can detect the phase signal of square wave, and exports this detection signal to the electric current interception unit;

One electric current interception unit, the detection signal that the receiving phase detecting unit is exported, and with compare in the electric current that driving transformer intercepted, and comparative result is feedback to the square wave controller;

One square wave controller receives the comparative result of being exported by the electric current interception unit, and controls the dynamic frequency of doing of electronic switch according to this result.

3. a phase-locked real merit Current Control circuit is characterized in that, comprises:

One direct current power supply provides a direct current signal to electronic switch;

One electronic switch receives the direct current signal of direct supply output, and it is switched to square-wave signal exports driving transformer and phase detection unit to;

One driving transformer receives the square-wave signal of electronic switch output, and exports to load and use after the processing of boosting;

One phase detection unit receives the square-wave signal of electronic switch output, and can detect the phase signal of square wave, and exports this detection signal to the electric current interception unit;

One electric current interception unit, the detection signal that the receiving phase detecting unit is exported, and with compare in the electric current that load intercepted, and comparative result is feedback to the square wave controller;

One square wave controller receives the comparative result of being exported by the electric current interception unit, and controls the dynamic frequency of doing of electronic switch according to this result.

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